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  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>

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<script>
  let s1 = Symbol('123')
  let s2 = Symbol('123')
  // symbol是唯一的 表示独一无二的值
  console.log(s1 === s2) //false
  console.log(s1) //Symbol(123)

  let obj = {
    age: 500,
    [Symbol('name')]: Symbol('李唯一')
  }
  // 无法遍历
  for (const key in obj) {
    console.log(key)
  }
</script>

</html>